WO2009099289A2 - Procédé de réduction des interférences dans un système cellulaire basé sur le multiplexage par répartition orthogonale de la fréquence - Google Patents

Procédé de réduction des interférences dans un système cellulaire basé sur le multiplexage par répartition orthogonale de la fréquence Download PDF

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WO2009099289A2
WO2009099289A2 PCT/KR2009/000527 KR2009000527W WO2009099289A2 WO 2009099289 A2 WO2009099289 A2 WO 2009099289A2 KR 2009000527 W KR2009000527 W KR 2009000527W WO 2009099289 A2 WO2009099289 A2 WO 2009099289A2
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cell
resource
resource group
interference
frequency reuse
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PCT/KR2009/000527
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English (en)
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WO2009099289A3 (fr
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Jae Young Ahn
Hyun Kyu Chung
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Electronics And Telecommunications Research Institute
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Priority claimed from KR1020080089608A external-priority patent/KR20090085504A/ko
Application filed by Electronics And Telecommunications Research Institute filed Critical Electronics And Telecommunications Research Institute
Priority to US12/866,103 priority Critical patent/US8750885B2/en
Publication of WO2009099289A2 publication Critical patent/WO2009099289A2/fr
Publication of WO2009099289A3 publication Critical patent/WO2009099289A3/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/02—Resource partitioning among network components, e.g. reuse partitioning
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes
    • H04J11/0023—Interference mitigation or co-ordination
    • H04J11/005—Interference mitigation or co-ordination of intercell interference
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0003—Two-dimensional division
    • H04L5/0005—Time-frequency
    • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0037—Inter-user or inter-terminal allocation
    • H04L5/0041—Frequency-non-contiguous

Definitions

  • the present invention relates to an interference mitigation method based on an orthogonal frequency division multiple access (OFDMA), hereinafter, referred to as "OFDMA", and more particularly, to a cell interference mitigation method of adopting fractional frequency reuse for a concept of interference avoidance for enhancing efficiency of a user's spectrum in a cell boundary or of integrating cell removing schemes using multiple receiving antennas and a diffusion code.
  • OFDMA orthogonal frequency division multiple access
  • interference averaging there is a mechanism for partially applying interference avoidance of a frequency reuse concept to divide overall resources into a resource space and a secondary resource space.
  • traffic with similar properties are collected and allocated to a single resource space and a single secondary resource space.
  • the conventional method introduced matching traffic having similar properties with each other in multi cell environments.
  • all cells are divided into three frequency reuse patterns, and one resource space is divided into three secondary resource spaces, and each of three cells mainly uses one of the three secondary resource spaces and allows transmission with a relatively large electrical power and for the remaining two secondary resource spaces, a small, restricted amount of electrical power is permitted for the transmission to limit the interferences to the adjacent cells.
  • a user having inferior channel properties in a cell boundary communicates with a frequency reuse factor of 3 using 1/3 of overall resources
  • another user having superior channel properties may perform communications without affecting users around a base station.
  • a frequency reuse method based on an identical concept of the above conventional method, users inside a cell operate with a frequency reuse factor of 1, and users in a cell boundary operate with a frequency reuse factor of 3.
  • overall resources there are common resources shared by the users inside a cell, and the remaining resources are divided into three parts for users in the cell boundary, for each of the cells.
  • each terminal has a different level of interference affecting adjacent cells for each adjacent base station, and looks up a base station which the terminal is affected by the greatest interference.
  • each of the base stations collects terminals with great interferences and receives the collected interferences at one time. This mechanism would seldom result in a great level of interference, yet it is overall beneficial since the interference level is significantly low in most cases. Also, the interference level is low as well when a terminal in the cell boundary is being serviced, thereby improving the performance.
  • the above method is for the uplink, and a method for a downlink also intends to a direction of utilizing great interference, here, benefit may be obtained from reducing an electrical power in base stations which gives great interference.
  • a terminal performs communication when electrical power in a base station with great interferences are reduced.
  • the operations may differ, yet geographical dispositions of the terminals are largely similar, and this mechanism of downlinks is relatively simpler than the previous mechanism of uplinks.
  • the present invention provides an inter-cell interference mitigation method for a user in a cell boundary by performing unified inter-cell interference removal using a multiple receiving antenna and a spreading code as well as by employing a fractional frequency reuse scheme with an interference avoidance concept, in an orthogonal frequency division multiple access (OFDMA)-based cellular system, thereby enhancing spectrum efficiency of the user in the cell boundary.
  • OFDMA orthogonal frequency division multiple access
  • an inter-cell interference mitigation method in an orthogonal frequency division multiple access (OFDMA)-based cellular system including: dividing wireless resources into a resource group for fractional frequency reuse and a resource group for removing inter-cell interference; and re-dividing the resource group for fractional frequency reuse into particular resource groups numbering the same as a number of cell types of fractional frequency reuse, and applying a maximum transmission power to a particular resource group according to a cell type for fractional frequency reuse.
  • OFDMA orthogonal frequency division multiple access
  • an inter-cell interference mitigation method in an OFDMA-based cellular system including: dividing wireless resources into a resource group for fractional frequency reuse and a resource group for removing inter-cell interference; re-dividing the resource group for fractional frequency reuse into particular resource groups numbering the same as a number of cell types of fractional frequency reuse; re-dividing the resource group for removing inter-cell interference into particular resource groups for each spreading factor; allocating a particular resource group depending on a user in a cell boundary or a user inside a cell; allocating a resource in the resource group for each spreading factor according to required performance of a downlink control channel; spreading each transmission data symbol using a spreading code vector combined with each unit resource, and transmitting the spread transmission data symbol using a basic resource configuring a corresponding unit resource, when the resource group for removing inter-cell interference of the spreading factor is allocated; and restoring a data symbol according to a spreading factor by receiving required signals or interference signals.
  • an inter-cell interference mitigation method in an OFDMA-based cellular system including: configuring a unit resource in a particular resource group of each spreading code for removing inter-cell interference with basic resources which are farthest away from a frequency and time domain; combining a pseudo random code vector with each unit resource according to a cell type or a cell identification (ID) of a corresponding cell; spreading each transmission data symbol using the pseudo random code vector combined with the unit resource, and transmitting the spread transmission data symbol using a basic resource configuring a corresponding unit resource, when a resource group for removing inter-cell interference of a specific spreading factor is allocated; and receiving the transmitted signals, removing inter-cell interference using dispreading and a MIMO detector, and restoring a required data symbol.
  • ID cell identification
  • an inter-cell interference mitigation method in an OFDMA-based cellular system including: configuring a unit resource in a particular resource group for each spreading code for removing inter-cell interference with basic resources which are closest from a frequency and time domain; combining each unit resource with an orthogonal coded vector according to a cell type of a corresponding cell; spreading each transmission data symbol using the orthogonal coded vector combined with the unit resource, and transmitting the spread transmission data symbol using a basic resource configuring a corresponding unit resource, when a resource group for removing inter-cell interference of a specific spreading factor is allocated; and receiving the transmitted signals, removing interference symbols using a different spreading code vector from a required data symbol via despreading, removing an interference symbol which uses an orthogonal code identical to the required data symbol, and restoring a required data symbol.
  • FIG.S. 1 and 2 are diagrams illustrating a fractional frequency reuse method for removing inter-cell interference according to an exemplary embodiment of the present invention
  • FIG. 3 is a diagram illustrating a detailed configuration of a resource group having a frequency reuse factor of 1 for removing inter-cell interference according to an exemplary embodiment of the present invention
  • FIG. 4 is a diagram illustrating a multiple-input multiple-output (MIMO) channel when there are two receiving antenna and there is a single inter-cell interference according to an exemplary embodiment of the present invention
  • FIG. 5 is a diagram illustrating an MIMO channel having two receiving antenna and three inter-cell interferences according to an exemplary embodiment of the present invention
  • FIG. 6 is a diagram illustrating a regular cell array when there are three or four cell types
  • FIG. 7 is a diagram illustrating a configuration of a resource group for removing inter-cell interference within each resource group according to a fractional frequency reuse method, when a cell boundary frequency reuse factor is 2, according to an exemplary embodiment of the present invention
  • FIG. 8 is a diagram illustrating a configuration of a resource group for removing inter-cell interference within each resource group according to a fractional frequency reuse method, when a cell boundary frequency reuse factor is 3, according to an exemplary embodiment of the present invention.
  • FIG. 9 is a flowchart illustrating an inter-cell interference mitigation method according to an exemplary embodiment of the present invention.
  • the present invention is based on a fractional frequency reuse method which can mitigate inter-cell interference by removing inter-cell interference using a multiple receiving antenna and a spreading code with respect to a downlink control channel which should be receivable by all terminals or for users in a cell boundary who is exposed to inter-cell interference due to irregular cell arrays or shadowing phenomenon, and provides the following access method described hereinafter.
  • Such access method configures, separately from resources employing a fractional frequency reuse method, a resource group having a frequency reuse factor of 1 for removing inter-cell interference, and may be combined with any fractional frequency reuse methods.
  • FIGS. 1 and 2 are diagrams illustrating a fractional frequency reuse for removing inter-cell interference according to an exemplary embodiment of the present invention.
  • a number of a resource group permitting higher maximum transmission power for users in a cell boundary varies according to a fractional frequency reuse method, and the resource groups permitting the higher maximum transmission power also vary per cell type.
  • the fractional frequency reuse method takes into consideration a location of the users in the cell boundary among the resource group permitted with the higher maximum transmission power or takes into consideration cell types of estimated interference signals, thereby mitigating inter-cell interference by not giving the interferences to the users in the cell boundary of adjacent cells or by allocating resources of the resource group with small interferences.
  • a resource group B having a frequency reuse factor of 1 is separately provided for removing the inter-cell interference, and this resource group B is allocated to configure uplink and downlink traffic channels and a control channel for terminals in the cell boundary.
  • FIG. 3 is a diagram illustrating a detailed configuration of a resource group having a frequency reuse factor of 1 for removing inter-cell interference.
  • wireless resources are divided into a wireless group A for fractional frequency reuse, and a resource group B for removing inter-cell interference.
  • the resource group B of each cell is further divided into separate resource groups according to spreading factors (SF) of spreading codes.
  • a unit resource of the resource group B1 consists of an SF 1 number of a basic resource, the SF 1 being a spreading factor of a corresponding resource group, and a basic resource consists of one OFDM symbol and one subcarrier in an OFDM signal.
  • unit resources of the resource groups B2 and B3 consist of an SF 2 number and an SF 3 number of a basic resource respectively.
  • Each of the unit resources in the resource groups B1, B2, and the others consists of basic resources of identical frequency and time per cell, and each transmission data symbol is spread using a unit resource of a selected resource group and is transmitted using an appropriate spreading code multiplying the spread transmission data symbol SF i times.
  • the following allocation method is about allocating a resource of the resource groups being configured according to the above described method to each channel.
  • a resource of the resource group A for fractional frequency reuse is basically allocated.
  • a spreading factor is determined according to requirements and performance for a corresponding channel and a resource in a resource group of the spreading factor within the resource group for removing inter-cell interference is allocated.
  • a multiple receiving antenna is exclusively used to remove the inter-cell interference.
  • N Rx When a number of a receiving antenna is N Rx and a number of a transmission antenna N Tx is equal to N Rx or less than N Rx , the N Rx number of symbols may be simultaneously transmit and restore the N Rx number of symbols using a Multi-Input Multi-Output (MIMO) receiving technique.
  • MIMO Multi-Input Multi-Output
  • FIG. 4 is a diagram illustration a MIMO channel when there are two receiving antennas and there is a single inter-cell interference according to an exemplary embodiment of the present invention.
  • N Tx 1
  • N Rx 2
  • x 1 is a desired symbol
  • x 2 is an inter-cell interference
  • a receiver with two receiving antennas can restore x 1 using a MIMO detector, thereby removing x 2 .
  • N Rx > 2 it is also possible to remove an N Rx -1 number of interferences in the same manner.
  • FIG. 5 is a diagram illustrating a MIMO channel having two receiving antennas and three inter-cell interferences according to an exemplary embodiment of the present invention.
  • Equation 1 represents a received code vector in a receiver.
  • z may be defined as in Equation 4.
  • orthogonal codes such as Walsh codes are , since the same number of orthogonal codes as a length of the code exist. Consequently, since , z may be defined as the following Equation.
  • Equation 6 z may be divided into the following two Equations in Equation 6.
  • x A and x B may be detected using a 2 x 2 MIMO detector, and in order to detect a desired symbol, MIMO detection is required to be performed with respect to vectors including the desired symbol, between x A and x B .
  • x A may be detected using a 2 x 2 MIMO detector as the above, however, as x B may be detected using a matched filter such described as below instead of using the MIMO detector.
  • a desired symbol and an interference symbol using another spreading code vector are initially removed through despreading in either a receiver or a transmitter using the spreading factor.
  • an interference symbol using an identical spreading code vector to the desired data symbol is removed via a MIMO detector in the receiver.
  • a number of interference removable via the MIMO detector is N Rx -1 in the case a number of antennas is N Rx , and for this, N Rx x N Rx MIMO detectors are required.
  • a cell array in a cellular system as a number of a pattern of resource reuse is required to be at least three, at least three cell types for orthogonal code vector reuse are required to be defined and an orthogonal code is required to be allocated accordingly.
  • a basic rule for the allocation is that, a number of cell types using the identical orthogonal code vector within an entire cell type group should be equal to or smaller than a reference number of receiving antennas in order to remove interference using the MIMO detector.
  • a number of receiving antennas in each of terminals and base stations are not constant, however an appropriate reference number should be established by considering a system capacity or spectrum efficiency of users in a cell boundary.
  • an appropriate reference number should be established by considering a system capacity or spectrum efficiency of users in a cell boundary.
  • the case that there are two reference antennas will be described in this specification. In such an assumption, in the case that there are at least three receiving antennas, it is possible to remove more interference using the identical code vectors in comparison to the case of using two receiving antennas.
  • FIG. 6 is a diagram illustrating a regular cell array when there are three or four cell types.
  • FIG. 6 it is illustrated a regular cell array in the case there are three or four cell types.
  • the simplest way to allocate an orthogonal signal is to follow the above described basic rule for the allocation, and to allocate the orthogonal code vector fixed in each cell type.
  • exemplary embodiments for the allocation of the orthogonal code vectors are as follows:
  • the optimal orthogonal code vector sequence groups are subsets of each of sequence groups in the case there are four cell types.
  • s number of cell types which use the identical code vector among all cell types is equal to or less than a reference number of a receiving antenna of 2, that is 2 or 1.
  • a frequency to use the identical code vector is the same as 1/3 the frequency
  • a frequency of each cell type using the identical code vector to other cell types is the same as 1/3 the frequency.
  • the frequency for one cell type to use the identical code vector at an identical time point to other cell types is the same as 1/3 the frequency.
  • a number of cell types using an identical code vector at an identical point in time should not exceed a reference number of receiving antennas.
  • a frequency of each cell type which uses an identical code vector at an identical point in time to each of other cells, is required to be as close as possible to a frequency of each of other cells(For interference diversification and performance averaging).
  • the cell type for such orthogonal code reuse is not necessary to be identical to a cell type for fractional frequency reuse.
  • the spreading factor cannot be used to directly remove the desired data symbol and the other code vectors. Instead, the spreading factor may be used to improve correlation between channel response properties of the basic resources which configure the unit resource for data symbol transmission. Also, since a poly-phase sequence may be used for the pseudo noise code instead of a binary sequence, relatively more code vectors may exist than the identical SF. Consequently, a range of selections for a length of code vector sequence for allocating a spreading code sequence and a number of cell types and the others is wider. Thus, it is possible to have the cell type for allocation of the spreading code to be identical to a cell type of fractional frequency reuse, and in an extreme case, it is possible to have the cell type for allocation of the spreading code to be identical to cell identification (ID).
  • ID cell identification
  • An approach method of inter-cell interference mitigation method for users in a cell boundary who are exposed to inter-cell interference caused from irregular cell arrays or caused by shadowing based on fractional frequency reuse by removing inter-cell interference using a multiple receiving antenna and a spreading code is to configure a resource group for removing inter-cell interference within each of resource groups for fractional frequency reuse. Such an approach also may be used in combination with any other fractional frequency reuse method.
  • FIG. 7 is a diagram illustrating a configuration of a resource group for removing inter-cell interference within each resource group according to a fractional frequency reuse method, when a cell boundary frequency reuse factor is 2, according to an exemplary embodiment of the present invention.
  • FIG. 8 is a diagram illustrating of a configuration of a resource group for removing inter-cell interference within each resource group according to a fractional frequency reuse method, when a cell boundary frequency reuse factor is 3, according to an exemplary embodiment of the present invention.
  • FIGS. 7 and 8 a configuration, according to an exemplary embodiment of the present invention, of a resource group for removing inter-cell interference within each resource group for fractional frequency reuse of when a cell boundary frequency reuse factor is 2, reference numerals 710 and 720 and of when a cell boundary frequency reuse factor is 3, reference numerals 810 and 820, is illustrated.
  • particular resource groups A1-B, A2-B, and A3-B are respectively provided for removing inter-cell interference within existing resource groups A1, A2, and A3, and the resource groups are allocated to configure uplink and downlink traffic channels for terminals on a cell boundary and to configure a control channel for specific users.
  • Each of the particular resource groups A1-B, A2-B, and A3-B is re-divided into separate resource groups for each spreading factor of a spreading code.
  • A1-B is divided into A1-B1, A1-B2, and ..., and a unit resource of A1-B1, A1-B2, and ..., respectively consists of an SF 1 , SF 2 , and ..., number of basic resources.
  • Each unit resource of the resource groups A1-B1, A1-B2, and ... consists of basic resources with identical time and frequency per cell, and each transmission data symbol is spread SF i times using the unit resource of a selected resource group to be transmitted.
  • a method for allocating the resource of the resource group configured as the above to each channel is as follows: First, for users in the cell boundary with an estimated SIR being less than a predetermined threshold, with respect to both a case of respectively allocating a particular resource group for each spreading factor for removing inter-cell interference among resource groups permitted with a maximum transmission power, and a case of allocating a resource except for the portion for removing inter-cell interference, a resource of a group, which can expect largest spectrum efficiency or a similar metric to the largest spectrum efficiency when considering an estimated SNR, a number and a type of interferences, an SIR per interference signal, a number of antennas in a receiver/transmitter, and required performance, is allocated. For users inside the cell with an SIR being greater than a predetermined threshold, a resource of a particular resource group with lower transmission power permitted (including the resource group for removing inter-cell interferences inside a cell) is allocated first.
  • a transmission and reception method using the particular resource groups for removing inter-cell interference is, besides the resource employing fractional frequency reuse which is the first access method, identical to the case of configuring a resource group whose frequency reuse factor for removing inter-cell interference is 1.
  • a base station and a terminal in a cellular system may have multiple transmission antennas as well as multiple receiving antennas.
  • To remove interference using multiple receiving antennas it is convenient not to apply spatial multiplexing and spatial division multiple access. Consequently, when a number of transmission antennas is at least two, it is possible to enhance a capacity of a link by simultaneously employing transmission diversity scheme using two transmission antennas.
  • FIG. 9 is a flowchart illustrating an inter-cell interference mitigation method according to an exemplary embodiment of the present invention.
  • an ODFMA cellular system divides wireless resources into a resource group for fractional frequency reuse and a resource group for removing inter-cell interference.
  • the OFDMA cellular system may divide the wireless resources into the resource group for fractional frequency reuse and the resource group for removing inter-cell interference with a frequency reuse factor is 1.
  • the OFDMA cellular system re-divides the resource group for fractional frequency reuse into particular resource groups numbering the same as a number a number of cell types of fractional frequency reuse.
  • the OFDMA cellular system re-divides the resource group for fractional frequency reuse into particular resource groups numbering the same as the number of cell types of fractional frequency reuse, and applies a maximum transmission power to a particular resource group according to a cell type for fractional frequency reuse.
  • the OFDMA cellular system re-divides the resource group for removing inter-cell interference into the particular resource groups for each the spreading factor.
  • the OFDMA cellular system re-divides the resource group for removing inter-cell interference into the particular resource groups for each spreading factor, and re-divides the re-divided resource groups for each spreading factor into a unit resource consisting of basic resources numbering the same as a number of a spreading factor in an identical location in all cells, and combines a spreading code vector with each unit resource according to a corresponding cell type.
  • the OFDMA cellular system allocates the particular resource groups depending on whether a user is inside a cell or a user is in a cell boundary.
  • the OFDMA cellular system may allocate a particular resource set in which a greater transmission power than a reference value is allowed, among the divided particular resource group for fractional frequency reuse, to the user in the cell boundary whose estimated SIR is less than a threshold.
  • the OFDMA cellular system may allocate, with respect to all cases of respectively allocating the divided particular resource group for each spreading factor, a resource in a resource group capable of estimating a greatest spectrum efficiency or a resource in a group capable of estimating a similar metric to the greatest spectrum efficiency, based on an estimated SNR, a number of interferences, an SIR for each interference signal, a number of transmission antennas, and a required performance.
  • the OFDMA cellular system may allocate a resource in the divided resource group for fractional frequency reuse to the user inside the cell whose SIR is greater than a threshold.
  • the OFDMA cellular system may initially allocate the resources of the resource group for each spreading factor according to the required performance of a downlink control channel.
  • the OFDMA cellular system may allocate the resources of the resource group for each spreading factor according to the required performance of a downlink control channel, which is receivable by all terminals.
  • the OFDMA cellular system may spread each transmission data symbol using a spreading code vector combined with each unit resource, and transmit the spread transmission data symbol using a basic resource which configures a corresponding unit resource, when the resource group for removing inter-cell interference of the spreading factor is allocated.
  • the OFDMA cellular system may receive a desired signal or interference signals, and restore a data symbol according to the spreading factor.
  • a spreading factor is 1
  • the OFDMA cellular system may restore the desired data symbol using a MIMO detector in operation S970.
  • the spreading factor is more than 2
  • the OFDMA cellular system may restore the desired data symbol by removing inter-cell interference using a MIMO detector based on multi receiving antennas and dispreading using the spreading vectors of the desired data in operation S970.
  • the present invention may mitigate inter-cell interferences by employing a fractional frequency reuse method based on interference avoidance, improve spectrum efficiency of users in a cell boundary by removing inter-cell interferences which have not been reduced to a predetermined level by irregular cell arrays or shadowing using multiple receiving antennas and a spreading code, and improve receiving performance for users in the cell boundary by removing inter-cell interferences of a downlink control channel which is receivable in all terminals.

Abstract

L'invention concerne un procédé de réduction des interférences intercellulaires dans un système cellulaire basé sur le multiplexage par répartition orthogonale de la fréquence (MROF) qui consiste: à diviser les ressources sans fil en un groupe de ressources pour la réutilisation des fréquences des canaux à demi-débit et en un groupe de ressources pour l'élimination des interférences intercellulaires; et à rediviser le groupe de ressources pour la réutilisation des fréquences des canaux à demi-débit en groupes de ressources particuliers numérotés selon un certain nombre de types de cellules de la réutilisation des fréquences des canaux à demi-débit, et à appliquer une puissance de transmission maximale à un groupe de ressources particulier en fonction du type de cellule destiné à la réutilisation des fréquences des canaux à demi-débit.
PCT/KR2009/000527 2008-02-04 2009-02-04 Procédé de réduction des interférences dans un système cellulaire basé sur le multiplexage par répartition orthogonale de la fréquence WO2009099289A2 (fr)

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KR10-2008-0011326 2008-02-04
KR20080011326 2008-02-04
KR10-2008-0089608 2008-09-11
KR1020080089608A KR20090085504A (ko) 2008-02-04 2008-09-11 직교 주파수 분할 다중 접속 기반의 셀룰러 시스템에서의 간섭 완화 방법

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CN101841819A (zh) * 2010-05-06 2010-09-22 工业和信息化部电信传输研究所 降低lte系统多个小区pdcch干扰的调度方法和装置
WO2012054898A3 (fr) * 2010-10-22 2012-07-26 Qualcomm Incorporated Systèmes, appareils et procédés pour faciliter la réutilisation de fréquences pour des canaux de commande de liaison descendante
GB2492453A (en) * 2011-06-30 2013-01-02 Ibm Sharing frequencies in an OFDM-based wireless communication system
WO2015038996A1 (fr) * 2013-09-16 2015-03-19 Qualcomm Incorporated Réutilisation de fréquence fractionnaire sur la base de la mobilité
WO2018133121A1 (fr) * 2017-01-23 2018-07-26 华为技术有限公司 Procédé et dispositif de communication sans fil
CN108401299A (zh) * 2017-02-08 2018-08-14 中兴通讯股份有限公司 一种上行业务实现方法及系统、主站及端站

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ES2298696T3 (es) * 2004-05-04 2008-05-16 Alcatel Lucent Metodo de coordinacion de la interferencia intercelular con planificacion de potencia en un sistema de comunicacion movil ofdm.
US8068785B2 (en) * 2005-09-06 2011-11-29 Electronics And Telecommunications Research Institute Method for resource partition, assignment, transmission and reception for inter-cell interference migration in downlink of OFDM cellular systems
US8005175B2 (en) * 2006-03-17 2011-08-23 Futurewei Technologies, Inc. Method and apparatus for interference mitigation in an OFDMA-based communication system

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CN101841819A (zh) * 2010-05-06 2010-09-22 工业和信息化部电信传输研究所 降低lte系统多个小区pdcch干扰的调度方法和装置
US8681719B2 (en) 2010-10-22 2014-03-25 Qualcomm Incorporated Systems, apparatus and methods for facilitating frequency reuse for downlink control channels
WO2012054898A3 (fr) * 2010-10-22 2012-07-26 Qualcomm Incorporated Systèmes, appareils et procédés pour faciliter la réutilisation de fréquences pour des canaux de commande de liaison descendante
US9247538B2 (en) 2011-06-30 2016-01-26 International Business Machines Corporation Sharing frequencies in an OFDM-based wireless communication system
GB2492453B (en) * 2011-06-30 2014-04-23 Ibm Sharing frequencies in an OFDM-based wireless communication system
US9125062B2 (en) 2011-06-30 2015-09-01 International Business Machines Corporation Sharing frequencies in an OFDM-based wireless communication system
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GB2492453A (en) * 2011-06-30 2013-01-02 Ibm Sharing frequencies in an OFDM-based wireless communication system
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